如何获取当前电池电量百分比？

Question

我正在创建一个电池监视器应用程序，并且尝试显示当前的电池百分比。我有一个广播接收器，正在监听...

<action android:name="android.intent.action.BATTERY_CHANGED" />

在接收器中我有以下代码。

int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);

currentBatteryLevel = level / (float) scale;

Toast.makeText(context, "Current battery level: " + Float.toString(currentBatteryLevel) + "%", Toast.LENGTH_SHORT).show();

由于某种原因，结果总是Current battery level: 1.0%......我哪里出错了？

编辑：

接收者在清单中注册为...

<receiver android:name=".PowerMonitorReceiver">
    <intent-filter>
        <action android:name="android.intent.action.ACTION_POWER_CONNECTED" />
        <action android:name="android.intent.action.ACTION_POWER_DISCONNECTED" />
        <action android:name="android.intent.action.BATTERY_LOW" />
        <action android:name="android.intent.action.BATTERY_OKAY" />
        <action android:name="android.intent.action.BATTERY_CHANGED" />
    </intent-filter>
</receiver>

我的接收器是...

com.garciaericn.t2d 包；

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.BatteryManager;
import android.util.Log;
import android.widget.Toast;

public class PowerMonitorReceiver extends BroadcastReceiver {

    private static final String TAG = "PowerMonitorReceiver.TAG";
    private float currentBatteryLevel;

    @Override
    public void onReceive(Context context, Intent intent) {



        // Obtain action from intent to check which broadcast is being received
        String action = intent.getAction();

        // Perform action according to type
        switch (action) {
            case (Intent.ACTION_BATTERY_CHANGED): {
                Log.i(TAG, "Battery has changed");

                int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
                int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);

                currentBatteryLevel = (level * 100) / (float) scale;

                Toast.makeText(context, "Current battery level: " + Float.toString(currentBatteryLevel) + "%" + " level: " + level + " scale: " + scale, Toast.LENGTH_LONG).show();

                break;
            }
            case (Intent.ACTION_POWER_CONNECTED): {
                Log.i(TAG, "Power connected");

                int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
                boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING || status == BatteryManager.BATTERY_STATUS_FULL;

                int chargePlug = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
                boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
                boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC;

                String chargingType = null;

                if (usbCharge) {
                    chargingType = "USB";
                } else if (acCharge) {
                    chargingType = "AC Power";
                }

                if (isCharging && chargingType != null) {
                    Toast.makeText(context, "Device is charging via: " + chargingType, Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(context, "Device is charging.", Toast.LENGTH_SHORT).show();
                }
                break;
            }
            case (Intent.ACTION_POWER_DISCONNECTED): {
                Log.i(TAG, "Power disconnected");
                Toast.makeText(context, "Power Disconnected", Toast.LENGTH_SHORT).show();
                break;
            }
            case (Intent.ACTION_BATTERY_LOW): {
                Log.i(TAG, "Battery low");
                Toast.makeText(context, "Battery low", Toast.LENGTH_SHORT).show();
                break;
            }
            case (Intent.ACTION_BATTERY_OKAY): {
                Log.i(TAG, "Battery Okay");
                Toast.makeText(context, "Battery Okay", Toast.LENGTH_SHORT).show();
                break;
            }
        }
    }
}

Answer 1

我认为已经很晚了，但解决方案很简单。根据此链接，如果您在 xml 中注册了广播接收器，您将不会收到 BATTERY_CHANGED 的更新，因为它是粘性广播。

您需要在 java 程序中注册广播接收器，如下所示。

IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = context.registerReceiver(null, ifilter);

int level = batteryStatus.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
int scale = batteryStatus.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
float batteryPct = (level * 100) / (float)scale;

注意：即使您将“null”传递为接收器，您仍然可以接收所有所需的电池数据。您还可以传递 Receiver 类而不是“null”来进行连续监控，但请注意，这会耗尽您的设备电池，因为这些广播经常抛出。